15w-40

[UnlimitedLJ05]

Is it safe to use a 15w-40 in a 2005 Jeep 4.0L with 93k on it leaving in Texas? Engine seems smoother with it but, I have heard conflicting stories saying its not ok and others saying it was better because its a loose engine unlike modern tighter engines. Thanks.

 

[stumblnyj]

It should be fine as long as it doesn'y get cold where you live and you don't plan on traveling to ND in the winter.

 

[UnlimitedLJ05]

So as long as its not single digit's its okay then? I can only think of a handful of mornings in the winter here where its gotten down to like 10 degrees but, we are talking record book tempartures for here that don't happen often and when they do its a week at best. 30s and upper 20s are the norm.

 

[JohnnyO]

A 2005 IS a modern engine. Diesel-spec oil like 15w-40 has more zinc in it than modern gas engine oil but as far as I know all modern engines have roller lifters so the extra zinc is not necessary. You didn't say where you were moving to but I would use a high-mileage 5w-30 or 10w-30 like Max Life and call it good.

 

[UnlimitedLJ05]

I won't be moving that I know of. I forgot to mention its a 4.0L inline six. I like the maxlife but, it seems the Jeep would tick some when it got hot out with 5w-30 or 10w-30. For some strange reason it seems to harldly tick at all with 15w-40 at least in the summer temps. I haven't used it in the winter or cooler months so I don't know.

 

[JohnnyO]

I won't be moving that I know of.

My mistake, I misread that and thought you said "leaving Texas" and not "leaving in Texas".
In the heat down there 15w-40 should be okay. I have run Rotella T-5 10w-30 diesel-spec in my 97 2.5L and the used oil analysis was very good but for some reason oil consumption was very high with it, 4 quarts in 3000 miles, so I went back to Max Life. You could try the Rotella T-5 when the weather is cooler and see if it keeps the noise down also.